The father of an imprisoned Iranian-American journalist in Tehran says she has gone on a hunger strike to protest her eight-year jail sentence for espionage.

Reza Saberi said Saturday his daughter, Roxana, is on her fifth day of a hunger strike and will continue to refuse food until Iranian authorities release her from prison.

Saberi's lawyer, Abdolsamad Khorramshahi, appealed her sentence earlier in the day.

An Iranian court sentenced the 31-year-old journalist on April 18 after she was convicted during an internationally criticized closed-door trial.  The U.S. State Department says the spying charges are baseless.

Iranian President Mahmoud Ahmadinejad has said he will not intervene in the Saberi case.  But he has called on the judiciary to ensure that Saberi is allowed a full defense during the appeal process.  And the head of Iran's judiciary has ordered a "quick" and "fair" appeal.

Saberi's parents have visited the imprisoned journalist, and they said she seemed to be in good health.

This case comes at a time when U.S. President Barack Obama is seeking a dialogue with Iran to ease decades of mistrust between the two countries.

Saberi worked as a freelance journalist in Iran for U.S. and British news outlets.  She was arrested in late January for allegedly working in the country without valid press credentials.  Her father says Iranian officials tricked her into making incriminating statements by telling her that doing so would enable her release.

Some information for this report was provided by AP and Reuters.